The present invention relates to a phase adjusting method which, in a work with a recess formed around the axis of the work, positions the recess around the axis of the work. In addition, the present invention also relates to a recess machining apparatus and method for producing a work with a recess formed around its axis in which the recess of the work can be accurately positioned and then machined.
For example, a loading cam mechanism of a troidal-type continuously variable transmission used as a transmission for a car includes a cam disk and a roller. The cam disk is formed in a disk shape which is symmetric with respect to the axis of the cam disk. Also, the cam disk includes an end face, which is formed symmetric with respect to the above-mentioned axis and extends in a flat manner along a direction meeting at right angles to the above-mentioned axis, and a plurality of cam surfaces each of which has a concave shape extending from the end face and is formed at positions spaced at equal intervals along the peripheral direction of the cam disk.
Each of the cam surfaces includes a pair of inclined surfaces respectively formed inclined with respect to the end face of the cam disk and opposed to each other, and an arc surface connecting the pair of inclined surfaces to each other.
To manufacture a work such as the above-mentioned cam disk which includes an end face formed symmetric with respect to the axis of the work and a plurality of cam surfaces respectively formed in a concave manner from the end face of the work and arranged at equal intervals along the peripheral direction of the work, normally, there is employed a manufacturing method which comprises the following two steps: that is, one is a rough machining step in which a cylindrical-shaped blank member is forged or cut to thereby produce once an intermediate product close in shape to the above-mentioned cam disk; and, the other is a finishing step in which a grinding operation or a similar finishing operation is executed on the thus produced intermediate product to thereby obtain a cam disk having a final shape.
The intermediate product 62 (which is hereinafter referred to as a work) obtained through the rough working step, as shown in FIG. 13 and in other figures, is formed in a disk shape which is symmetric with respect to the axis P2 thereof. The work 62 includes an end face 63, which is formed symmetric with respect to the axis P2 and extends in a flat manner along a direction meeting at right angles to the axis P2, and a plurality of recesses 64 which are respectively formed in a concave manner and are disposed at equal intervals along the peripheral direction of the work 62. By the way, these recesses 64 correspond to the above-mentioned cam surfaces.
When carrying out a grinding operation or a similar finishing operation on the work 62 obtained through the rough working step, it is necessary to position a tool such as a grindstone or the like at a position which corresponds to the above-mentioned recesses 64. For this reason, a proper position relationship between the recesses 64 and tool must be maintained by using means which can position or set the position of the recesses 64 around the axis P2 at a given position.
Conventionally, in carrying out a grinding operation or a similar finishing operation on the above-mentioned work 62, to keep a proper position relationship between the recesses 64 and tool, an operator positions the tool such as a grindstone or the like by hand in such a manner that it is contacted with the bottom 64a of the currently required one of the recesses 64. An operation to position the recess 64 and tool in this manner not only demands skill from the operator but also is liable to lower the positioning accuracy of the work 62 around the axis P2. Further, such positioning operation provides a low operation efficiency and is thus liable to increase the manufacturing cost of the work 62.
As the means for positioning the position of each of the recesses 64 around the axis P2 at a given position, it can be expected to use a positioning jig. A positioning jig of this type includes a projection which can be engaged with and matched to any one of the recesses 64. That is, when using such positioning jig, the projection thereof is engaged with and matched to the specific one of the recesses 64 to thereby position the work 62. However, a phase adjusting method using this type of positioning jig is found that it is liable to lower the positioning accuracy of the work 62 around the axis P2; for example, the positioning accuracy of the work 62 around the axis P2 is easy to vary.